Combination valve and safety pilot



Oct. 17, 1961 J. o. THORSHEIM 3,004,713

COMBINATION VALVE AND SAFETY PILOT Filed Nov. 21, 1957 A ssaaadINVENTOR.

JOSEPH O. THORSHEIM ATTORNEY United States Patent 3,004,713 COMBINATIONVALVE AND SAFETY PILOT Joseph 0. Thorsheim, Minneapolis, Minn., assignorto Minneapolis-Honeywell Regulator Company, Minneapolis, Minn., acorporation of Delaware Filed Nov. 21, 1957, Ser. No. 697,964 2 Claims.(Cl. 236-68) This invention relates to a combination valve and safetypilot and, more particularly, to a fluid pressure operated valve that isadapted to be actuated by two condition responsive controllers.

It is generally and broadly well known in the heating controls art toprovide a valve which is controlled by means responsive to roomtemperature and also responsive to the presence or absence of a pilotflame to cause closure of the valve in the event the room temperaturereaches the desired level or the pilot flame becomes extinguished.

One of the objects of this invention is to provide a much simpler,inexpensive, reliable and generally better fuel control device of theabove-mentioned type.

It is another object of this invention to provide a combination valveand safety pilot with a fluid power actuator that is fail safe. 7

Another object of the invention is to provide a fluid power actuator fora valve that provides negative feedback, to decrease the opening andclosing time constant for the valve under the control of a conditionresponsive means.

Still other objects of the invention will become apparent upon readingthe following detailed description of the invention in conjunction withthe accompanying draw ing wherein the only figure of the drawing showsthe invention in vertical cross-section and with portions thereof brokenaway.

The invention comprises a valve body 1 having a threaded inlet 2, athreaded outlet 3, and a valve seat 4 surrounding an opening 5 in apartition 6 between the inlet and outlet. A plate '7, secured to thebody 1 by bolts 8 closes the open bottom of the valve body while a plate9 is secured to the top of the body 1 by bolts 10 to seal the open topof the valve body.

A bellows 11 is brazed or otherwise secured at its open end 26 to thecover plate 9 and is similarly secured at its other closed end to avalve stem 12 which, in turn, is swivelly connected to a valve disc 13by a conventional ball and socket connection 14-45. The valve disc 13has a washer-shaped rubber valve seat 16 cemented or otherwise securedin a recess in the valve disc to provide a gas tight seal with the valveseat 14 and also to provide electrical insulation between the valve discand the valve seat. The normal position of the free end of the bellowswould be closer to the fixed end were it not for the fluid in thebellows.

A capillary tube 17 extends through a small opening 18 in the plate 9 toa bulb 19. The bulb 19, capillary tube 17 and bellows 11 may becompletely filled with a liquid that does not vaporize at pilot burnerflame temperature or it may be partially filled with a liquid thatvaporizes at or slightly below the temperature to be sensed by the bulb19. As illustrated, the bulb 19 has a heat conducting rod 20 extendingtherefrom that is adapted to be positioned in front of a pilot burner soas to sense the presence or absence of flame at the pilot burner toexpand or contract the bellows, respectively.

The other end of the bellows 11, which is connected to the valve 13, isfree to move in the outlet chamber to open and close the valve l3 uponexpansion and contraction of the bellows 11.

The fluid in the bellows 11 is adapted to be expanded by the supplyingof heat to the bellows in the form of electric current. A lead wire 21is electrically connected to the movable end of the bellows 11 throughthe valve stem 12 and to a terminal member 22 extending through aterminal block 23. The block 23 is secured over an opening 24 in theside wall of the valve body by means of bolts 25. As the fixed end ofthe bellows is electrically connected to the cover 9, current can bemade to pass through the bellows 11 from a power source 29, lead 2211the terminal 22, lead 21, bellows 11, plate 9, terminal 27 connected tothe plate 9, lead 27a, thermostat 28, lead 28a and power source 29.

The apparatus is illustrated as having a pilot burner flame playing onthe heat conducting rod 20 and with the room thermostat in satisfied oropen contact condition. Assuming that the valve is connected to a sourceof gas and to a main burner of a furnace, by pipes not shown, the fluidin the bulb 19 has been expanded as much as it will be by the pilotflame but still not enough to cause movement of the valve 13 from thevalve seat 4. Should the roomtherrnostat circuit be closed, as by a dropin temperature around the room thermostat, electric current will passthrough the bellows 11 from the movable end thereof to the closed endthereof and cause heating and further expansion of the fluid, toadditionally expand bellows 11. This additional expansion is suflicientto cause lifting of the valve 13 from the valve seat 4, to permit gas toflow from the source of supply to the main burner. The valve will remainopen until the main burner has supplied suificient heat to the spacesurrounding the thermostat to cause the thermostat control circuit to bebroken. Upon the discontinuance of the flow of current, the bellows 11will cool and cause closing of the valve 13.

Should there be a pilot flame failure while the valve is open under thecontrol of the room thermostat, fluid will flow from the bellows 11 backinto the bulb 19, to

cause closure of the valve 13 and provide safety shut 7 down. It is alsoto be noted that should there be any rupture of the bellows 11 while thevalve is open, the escape of fluid from the bellows 11 will cause safetyshut down. Therefore, the combination valve and safety pilot providesfail safe operation. If desired, a spring may be added to bias the valveclosed upon rupture of the bellows or bulb instead of relying on theresilience of the bellows itself to cause closure of the valve.

Since the bellows 11 is in the stream of the gas flowing from its sourceof supply to the main burner, the gas constantly provides a coolingefiect to the bellows as long as the valve is open. This cooling effectprovides what may be called negative feedback and tends to provideclosing of the valve even though the room thermostat is calling forheat. It will also be apparent that this cooling effect of the gas flowover the bellows will also help conduct the heat away from the bellows11 when the electrical current is cut ofl to thus provide quick shutdown of the valve when the room thermostat contacts open. When the valveis closed, there will be no gas flow over the bellows so that whenelectrical current is supplied to the bellows 11 to cause opening of thevalve, there will be quick heating of the bellows and quick opening ofthe valve in response to a call for heat by the room thermostat.

When the bulb and bellows are filled or partially filled with a liquidthat vaporizes at the desired control temperature, the pressure of thesystem will be the vapor pressure corresponding to the temperature ofthe coolest part of the enclosure. By proper calibration, the opening ofthe valve can only occur when both the bulb and bellows are raised tothe control temperature.

While I have disclosed the preferred embodiment of the invention, it isdeemed to be obvious that modifications may be made therein withoutdeparting from the spirit of the invention. Therefore, the scope of theinvention should be determined solely from the appended claims. 7

I claim: 7

1. The combination comprising a metallic valve body having an inlet andan outlet and a passage therebetween; a valve seat extending across saidpassage; an electrically nonconductive valve cooperable with said seat,and an expandable chamber made of metallic electrically conductivematerial in said passage between said seat and said outlet; meansoperably connecting said valve to a movable wall of said chamber;another portion of said chamber being fixed to and electricallyconnectedto said metallic valve body; a fluid-filled temperatureresponsive unit; a fluid passage between said chamber and said unit; andcondition responsive'rnean's including electrical connections to saidbody and to said moving wall for passing a current through said wallthereby electrically heating said chamber so as to cause expansion ofthe fluid in said chamber; the fluid in said chamber being heated by thejoint action of the temperature responsive unit and the electricalheating of said chamber by said condition responsive means; said fluidexerting suflicient expansive forces in said expandable chamber to opensaid valve only on the existence of the action of the temperatureresponsive unit and the simultaneous passage of electrical current tosaid expandable chamber.

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2. In a fluid flow device comprising a valve body having an inlet and anoutlet and a passage therebetween; a valve seat extending across saidpassage; a valve cooperable with said seat; an expandable chamber insaid passage and having a movable wall positioned in a direct heatexchange relationship I with the" main fluid flow through said valvebody; means operably connecting said valve to said movable Wall of saidchamber; saidchamber being fixed to said valve body; a fluid-filledtemperature responsive unit responsive to first heating means; a fluidpassage between said chamber and said unit; and second heating meansheating said chamber so as to cause expansion of the fluid in saidchamber tending to open said valve; the fluid in said chamber, passage,and unit being such that said chamber; can cause opening of said valveonly when both first and second heating means are operable.

References Cited in the file of this patent UNITED STATES PATENTS"1,612,246 Whittingham Dec. 28, 1926 1,886,439 Wells ---1 Nov. 8, 19322,047,878 Machintosh July 14, 1936 2,093,693 Dillman i Sept. 21, 19372,758,791 Jenkins Aug. 14, 1956

